#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main() {
	ios::sync_with_stdio(false);
    cin.tie(0);

	string n;
    cin >>n;
    int s = n.length();

    if(s == 1){
        if (stoi(n) < 3){
            cout << 1;
            return 0;
        }
    }

    bitset<50>maxi;

    for(int i = 0; i <s; i++){
        if(n[i]-'0' >= 3) maxi[s-1-i] = 1;
        else if(n[i]-'0' > 0){
            maxi[s-1-i] = 0;
            for(int j = s-2-i; j >= 0; j--) maxi[j] = 1;
            break;
        }
        else maxi[s-1-i] = 0;
    }

    unsigned long long db = maxi.to_ullong();

    cout<<db+1;
}